Characterization of the growth flux during the deposition of hydrogenated amorphous silicon by DC magnetron reactive sputtering.

摘要

A comprehensive study of the species impinging on the a-Si:H surface during growth by dc magnetron reactive sputtering using a silicon target in an Ar plus H{dollar}sb{lcub}rm2{rcub}{dollar} plasma is reported. Mass spectrometry, plasma probes, and computer simulations are utilized to determine the identities, fluxes, and energies of all species which are present during high-quality film growth.; A new technique, Double Modulated Beam Mass Spectrometry (DMMS) has been developed to determine the identities and energy distributions of neutral and ion species; DMMS has a signal-to-noise ratio which is over one hundred times greater than conventional techniques during the measurement of energetic species. Plasma probe measurements indicate a considerable plasma density near the substrate, with a total ion flux to the growth surface comparable to the arriving deposition flux.; The total energy and angular distributions of the sputtered species arriving at the substrate were obtained using fractal TRIM and Monte Carlo simulations of particle transport. The growth flux reaching the substrate is shown to be sensitive to the nascent sputtered particle distribution and gas-phase scattering potential. These simulations show that the energy distribution of depositing Si atoms is strongly dependent on not only the substrate position and orientation with respect to the target, but also on the argon gas pressure. For typical deposition conditions, the average energy was 9.7 eV, while the median energy was 4.2 eV. The reflected H flux was found to have a broad energy distribution, with an average energy of 145 eV. The computer simulation was also used to predict the physical sticking coefficient of the depositing species.; All of the above techniques are combined to estimate the magnitudes of the fluxes of the various sources of reactive H to the growth surface, and the energy deposited into the film.